Typhlocarcinops transversus Tesch, 1918

Ng, Peter K. L. & Rahayu, Dwi Listyo, 2020, A synopsis of Typhlocarcinops Rathbun, 1909 (Crustacea: Decapoda: Brachyura: Pilumnidae), with descriptions of nine new species from the Indo-West Pacific, Zootaxa 4788 (1), pp. 1-100 : 68-73

Typhlocarcinops transversus Tesch, 1918

( Figs. 57–60 )

Typhlocarcinops transversa Tesch, 1918: 212 ; pl. 13 fig. 3; Serène 1964: 233, text-fig. 12, pl. 20C; Zarenkov 1972: 237, pl. 4 fig. 2; Türkay 1986: 165, text fig. 59, pl. 4 figs. 15, 16; Ng 1987: 90.

Typhlocarcinops transversus — Ng et al. 2008: 144.

Typhlocarcinops marginata —Zarenkov 1972: pl. 5 fig. 1 (not Typhlocarcinops marginata Rathbun, 1914 ).

Material examined. Lectotype (here designated): male (8.0 × 4.1 mm) ( NNM-ZMA. CRUS.D.103003), station 47, Bay of Bima, north coast of Sumbawa, Flores Sea , 13–31 m, 8°0’29”S 118°34’40”E, Indonesia, coll. M. Webber, Siboga Expedition , 4 August 1899. Others : 1 female (7.3 × 5.0 mm) ( ZRC 2018.0271 ), station DW16, sand and gravel substrate, 6°09.803′S 104°57.976′E– 6°09.606′S 104°58.208′E, 92–103 m, Sunda Strait, Java, coll. SJADES, 26 March 2018; 2 females (7.3 × 5.3 mm, 5.5 × 3.8 mm) ( ZRC 2018.0272 ), Johor Shoal, Singapore, coll. May 1992; 2 males (7.5 × 5.5 mm, 6.5 × 4.7 mm) ( ZRC 2018.0272 ), station DW2370, sandy-muddy substrate, 8º33.6’N 123º8.3’E– 8º33.7’N 123º8.6’E, 92–96 m, Bohol Sea , Philippines; 1 male (6.0 × 4.0 mm) (NSMT-Cr 1214), Kagoshima, Japan, coll. 19 August 1974; 1 young male, 2 females (NSMT-Cr 5036), station 5, Kagoshima, 31º20.8’N 130º45.4’E, 70 m, Japan, coll. M. Imajima & M. Takeda, 18 April 1974.

Diagnosis. Carapace broad ( Figs. 57A, C , 58 , 59D ) about 1.4−2.0 times broader than long, surface smooth anteriorly, with granules posteriorly, regions indistinct, H-shaped gastro-cardiac grooves slightly indicated; anterolateral margin arcuate, lined with tiny granules and sparse setae, separated by 3 shallow depressions, forming 4 low, broad lobes; posterolateral surface and margin with scarce, scattered tubercles. Front ( Figs. 57A, B , 58C, D , 59A, D ) bilobed, with shallow median cleft, margin of each lobe slightly convex. Orbit ( Figs. 57B , 59A, B ) short, bulbous ocular peduncles filling orbit, immovable, cornea very small, well pigmented. Epistome ( Figs. 57B , 59A, B ) relatively broad, triangular median lobe with median suture. Antennal peduncles relatively long. Third maxilliped ( Fig. 60A ) with merus broad, squarish, outer and inner margins straight, ischium slightly broader, longer than merus, inner margin slightly shorter than outer margin, lower margin slightly oblique; exopod relatively stout, broad, tip reaching to just before distal edge of merus, inner margin with distinct tooth. Chelipeds slightly unequal in males, subequal in females ( Figs. 57A, B , 58A, B , 59C, E ), outer surface of fingers of chela smooth, with longitudinal ridge and scattered tubercles proximally on dactylus and fixed finger; surface of palm of major chela smooth, minor chela with scattered tubercles on lower outer surface; cutting edges of fingers with broad teeth; upper outer surface of carpus with small tubercles, smooth medially, inner angle without protuberance, with very short, broad tooth ( Figs. 57A , 58A, B ); lower outer surface of merus with scattered tubercles, margins covered with short setae. P2−P5 ( Figs. 57A , 58A, B ) proportionally long, fringe by sparse long setae on dorsal and ventral margins; merus of P5 not reaching front when folded. Fused thoracic sternites 1, 2 broadly triangular ( Figs. 57D , 59F ), proportionally broad; thoracic sternites 3, 4 partially fused, with only lateral suture discernible. Male pleon ( Figs. 57D , 59F , 60B ) broad, telson long, 1.9 times as long as somite 6, subtriangular with rounded distal margin. G1 ( Fig. 60 C–G) slender, upper part proportionally longer, slightly sinuous, distal part slightly curved, tapering, with blunt tip. Female pleon broad, telson subtriangular, somite 1 reaching coxae of fourth ambulatory legs, tapering to pointed edge; vulva ( Fig. 59G ) large, ovate.

Remarks. Typhlocarcinops transversus was described from a male (8.0 × 4.1 mm) and female (8.0 × 4.1 mm) from Sumbawa, Indonesia. Serène (1968) identified a female from the Sunda Straits as T. transversus , with Takeda & Miyake (1968) and Zarenkov (1972) adding this species to the Japanese and Vietnamese fauna, respectively. The G1 figured by Takeda & Miyake (1968: fig. 8a, b) is unusual in that the tip is distinctly truncated, markedly different from that of the type figured by Türkay (1986: text fig. 59) which has a bent tip. At about the same time, Ng (1987: 90) agreed with Takeda & Miyake’s (1968) observations that their specimens differed from T. transversus s. str. in having the anterior half of the carapace more sculptured, the anterolateral margin with three distinct blunt teeth separated by narrower spaces and the outer surface of the chela is smooth with the upper margin rounded ( Takeda & Miyake 1968: 571), and decided that the material should be referred to a new species which he named T. takedai , but this species is synonymized with T. marginatus in this study.

The Vietnamese specimen of Zarenkov (1972) matches T. transversus in general features, although the figure of the carapace appears rather schematic. The G1 figured (Zarenkov 1972: 237, pl. 4 fig. 2) agrees well with that figured for the type male by Türkay (1986: text fig. 59). The “ T. marginata ” reported by Zarenkov (1972: pl. 5 fig. 1) from Tonkin in Vietnam does not have an auriculiform anteroexternal angle of the merus of the third maxilliped; and in the general carapace appearance, seems to be more like T. transversus and is therefore assigned to this species for the time being.

Type locality. Bima, Sumbawa.

Distribution. Sumbawa in Lesser Sunda Islands, Singapore, Vietnam, Philippines and Japan. From muddy and soft substrates, at depths of 13– 103 m.

Figures

FIGURE 57. Typhlocarcinops transversus Tesch, 1918, holotype male (8.0 × 4.1 mm) (NNM-ZMA De 103.003), Sumbawa, Indonesia. A, overall habitus; B, frontal view of cephalothorax and chelae; C, dorsal view of carapace; D, anterior thoracic sternum and pleon.

FIGURE 58. Typhlocarcinops transversus Tesch, 1918. A, C, male (7.5 × 5.5 mm) (ZRC 2018.0272), Philippines; B, D, female (7.3 × 5.0 mm) (ZRC 2018.0271), Sunda Strait, Indonesia. A, B, overall habitus; C, D, dorsal view of carapace.

FIGURE 59. Typhlocarcinops transversus Tesch, 1918. A, C, F, male (7.5 × 5.5 mm) (ZRC 2018.0272), Philippines; B, E, G, female (7.3 × 5.0 mm) (ZRC 2018.0271), Sunda Strait, Indonesia; D, male (6.5 × 4.7 mm) (ZRC 2018.0272), Philippines. A, B, frontal view of cephalothorax; C, outer view of chelae; D, dorsal view of carapace; E, outer view of left chela; F, anterior thoracic sternum and pleon; G, sternopleonal cavity and vulvae.

FIGURE 60. Typhlocarcinops transversus Tesch, 1918. A, B, D–G, male (7.5 × 5.5 mm) (ZRC 2018.0272), Philippines; C, holotype male (8.0 × 4.1 mm) (NNM-ZMA De 103.003), Sumbawa, Indonesia. A, left third maxilliped; B, male pleon; C, right G1 (ventral view); D, left G1 (ventral view); E, left G1 (dorsal view); F, distal part of left G1 (ventral view); G, distal part of left G1 (dorsal view). Scales: A, D, E = 0.5 mm; B, C = 1.0 mm; F, G = 0.25 mm. C after Türkay (1986: text fig 59).